[test] Modernize hashing throughout the test suite

test/ClangImporter/objc_override.swift

@@ -110,7 +110,7 @@ class CallbackSubC : CallbackBase {
 
 //
 class MyHashableNSObject: NSObject {
-  override var hashValue: Int { // expected-warning{{override of 'NSObject.hashValue' is deprecated}}
+  override var hashValue: Int { // expected-error{{overriding non-open property outside of its defining module}} expected-error{{overriding non-@objc declarations from extensions is not supported}}
     return 0
   }
 }

test/Constraints/bridging-nsnumber-and-nsvalue.swift.gyb

@@ -38,7 +38,12 @@ extension Equatable {
     fatalError("hella cray")
   }
 }
-extension Hashable { public var hashValue: Int { fatalError("trill hiphy") } }
+extension Hashable {
+  public func hash(into hasher: inout Hasher) {
+    fatalError("trill hiphy")
+  }
+}
+
 extension CGSize: Hashable {}
 extension CGPoint: Hashable {}
 extension CGRect: Hashable {}

test/Constraints/bridging.swift

@@ -43,7 +43,7 @@ extension LazyFilterSequence.Iterator : _ObjectiveCBridgeable { // expected-erro
 
 
 struct BridgedStruct : Hashable, _ObjectiveCBridgeable {
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 
   func _bridgeToObjectiveC() -> BridgedClass {
     return BridgedClass()
@@ -72,13 +72,13 @@ struct BridgedStruct : Hashable, _ObjectiveCBridgeable {
 func ==(x: BridgedStruct, y: BridgedStruct) -> Bool { return true }
 
 struct NotBridgedStruct : Hashable {
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func ==(x: NotBridgedStruct, y: NotBridgedStruct) -> Bool { return true }
 
 class OtherClass : Hashable { 
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 func ==(x: OtherClass, y: OtherClass) -> Bool { return true }
 

test/DebugInfo/DumpTypeFromMangledName.swift

@@ -53,9 +53,7 @@ let _ = main()
 public struct tinky : Equatable, Hashable {
   internal let _value: Int
 
-  public var hashValue: Int {
-    return 0
-  }
+  public func hash(into hasher: inout Hasher) {}
 }
 
 public func == (lhs: tinky, rhs: tinky) -> Bool {

test/IRGen/Inputs/ObjectiveC.swift

@@ -47,7 +47,7 @@ public func _convertObjCBoolToBool(_ x: ObjCBool) -> Bool {
 }
 
 extension NSObject : Hashable {
-  @objc open var hashValue: Int { return 0 }
+  public func hash(into hasher: inout Hasher) {}
 }
 public func ==(x: NSObject, y: NSObject) -> Bool { return x === y }
 

test/IRGen/Inputs/usr/include/BridgeTestObjectiveC.h

@@ -2,6 +2,9 @@
 
 typedef struct _NSZone NSZone;
 
+typedef long NSInteger;
+typedef unsigned long NSUInteger;
+
 @protocol NSCopying
 - copyWithZone:(nullable NSZone*)z;
 @end
@@ -14,6 +17,5 @@ typedef struct _NSZone NSZone;
 + (void) initialize;
 
 @property (readonly, copy) NSString *description;
+@property (readonly) NSUInteger hash;
 @end
-
-typedef long NSInteger;

test/IRGen/keypaths.sil

@@ -13,7 +13,7 @@ public struct S: Hashable {
   public var z: C
   public var reabstracted: () -> ()
 
-  public var hashValue: Int { get }
+  public func hash(into hasher: inout Hasher)
   public static func ==(_: S, _: S) -> Bool
 }
 public class C: Hashable {
@@ -24,7 +24,7 @@ public class C: Hashable {
 
   public init()
 
-  public var hashValue: Int { get }
+  public func hash(into hasher: inout Hasher)
   public static func ==(_: C, _: C) -> Bool
 }
 

test/IRGen/objc_bridge.swift

@@ -191,7 +191,7 @@ class Bas : NSObject {
 
   deinit { var x = 10 }
 
-  override var hashValue: Int { return 0 }
+  override var hash: Int { return 0 }
 
   @objc func acceptSet(_ set: Set<Bas>) { }
 }

test/Inputs/clang-importer-sdk/swift-modules-without-ns/ObjectiveC.swift

@@ -77,6 +77,9 @@ extension NSObject : Equatable, Hashable {
   public var hashValue: Int {
     return hash
   }
+  public func hash(into hasher: inout Hasher) {
+    hasher.combine(hash)
+  }
 }
 
 public func == (lhs: NSObject, rhs: NSObject) -> Bool {

test/Inputs/clang-importer-sdk/swift-modules/ObjectiveC.swift

@@ -60,8 +60,8 @@ public struct Selector : ExpressibleByStringLiteral {
     self = sel_registerName(value)
   }
 
-  public var hashValue: Int {
-    return ptr.hashValue
+  public func hash(into hasher: inout Hasher) {
+    hasher.combine(ptr)
   }
 }
 
@@ -88,12 +88,16 @@ public func ~=(x: NSObject, y: NSObject) -> Bool {
 }
 
 extension NSObject : Equatable, Hashable {
-  @objc open var hashValue: Int {
-    return hash
-  }
-
   public static func == (lhs: NSObject, rhs: NSObject) -> Bool {
     return lhs.isEqual(rhs)
   }
+
+  public var hashValue: Int {
+    return hash
+  }
+
+  public func hash(into hasher: inout Hasher) {
+    hasher.combine(hash)
+  }
 }
 

test/Interpreter/FunctionConversion.swift

@@ -272,8 +272,9 @@ FunctionConversionTestSuite.test("CollectionUpCastsInFuncParameters") {
 protocol X: Hashable {}
 class B: X {
   var hashValue: Int { return 42 }
+  func hash(into hasher: inout Hasher) {}
   static func == (lhs: B, rhs: B) -> Bool {
-    return lhs.hashValue == rhs.hashValue
+    return true
   }
 }
 

test/Interpreter/collection_casts.swift

@@ -23,8 +23,8 @@ struct A : Preening, Hashable, Equatable {
     return lhs.value == rhs.value
   }
 
-  var hashValue: Int {
-    return value.hashValue
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
   }
 }
 

test/Interpreter/enum_equatable_hashable_correctness.swift

@@ -52,17 +52,29 @@ EnumSynthesisTests.test("CloseGenericValuesDoNotCollide") {
   expectNotEqual(Combo<String, Int>.both("foo", 3).hashValue, Combo<String, Int>.both("goo", 4).hashValue)
 }
 
+func hashEncode(_ body: (inout Hasher) -> ()) -> Int {
+  var hasher = Hasher()
+  body(&hasher)
+  return hasher.finalize()
+}
+
 // Make sure that if the user overrides the synthesized member, that one gets
 // used instead.
 enum Overrides: Hashable {
   case a(Int), b(String)
   var hashValue: Int { return 2 }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(2)
+  }
   static func == (lhs: Overrides, rhs: Overrides) -> Bool { return true }
 }
 
 EnumSynthesisTests.test("ExplicitOverridesSynthesized") {
   checkHashable(expectedEqual: true, Overrides.a(4), .b("foo"))
   expectEqual(Overrides.a(4).hashValue, 2)
+  expectEqual(
+    hashEncode { $0.combine(Overrides.a(4)) },
+    hashEncode { $0.combine(2) })
 }
 
 // ...even in an extension.
@@ -71,12 +83,18 @@ enum OverridesInExtension: Hashable {
 }
 extension OverridesInExtension {
   var hashValue: Int { return 2 }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(2)
+  }
   static func == (lhs: OverridesInExtension, rhs: OverridesInExtension) -> Bool { return true }
 }
 
 EnumSynthesisTests.test("ExplicitOverridesSynthesizedInExtension") {
   checkHashable(expectedEqual: true, OverridesInExtension.a(4), .b("foo"))
   expectEqual(OverridesInExtension.a(4).hashValue, 2)
+  expectEqual(
+    hashEncode { $0.combine(OverridesInExtension.a(4)) },
+    hashEncode { $0.combine(2) })
 }
 
 // Try an indirect enum.

test/Interpreter/struct_equatable_hashable_correctness.swift

@@ -40,17 +40,29 @@ StructSynthesisTests.test("CloseGenericValuesDoNotCollide") {
   expectNotEqual(PSI(a: "foo", b: 0).hashValue, PSI(a: "goo", b: 1).hashValue)
 }
 
+func hashEncode(_ body: (inout Hasher) -> ()) -> Int {
+  var hasher = Hasher()
+  body(&hasher)
+  return hasher.finalize()
+}
+
 // Make sure that if the user overrides the synthesized member, that one gets
 // used instead.
 struct Overrides: Hashable {
   let a: Int
   var hashValue: Int { return 2 }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(2)
+  }
   static func == (lhs: Overrides, rhs: Overrides) -> Bool { return true }
 }
 
 StructSynthesisTests.test("ExplicitOverridesSynthesized") {
   checkHashable(expectedEqual: true, Overrides(a: 4), Overrides(a: 5))
   expectEqual(Overrides(a: 4).hashValue, 2)
+  expectEqual(
+    hashEncode { $0.combine(Overrides(a: 4)) },
+    hashEncode { $0.combine(2) })
 }
 
 // ...even in an extension.
@@ -59,12 +71,18 @@ struct OverridesInExtension: Hashable {
 }
 extension OverridesInExtension {
   var hashValue: Int { return 2 }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(2)
+  }
   static func == (lhs: OverridesInExtension, rhs: OverridesInExtension) -> Bool { return true }
 }
 
 StructSynthesisTests.test("ExplicitOverridesSynthesizedInExtension") {
   checkHashable(expectedEqual: true, OverridesInExtension(a: 4), OverridesInExtension(a: 5))
   expectEqual(OverridesInExtension(a: 4).hashValue, 2)
+  expectEqual(
+    hashEncode { $0.combine(OverridesInExtension(a: 4)) },
+    hashEncode { $0.combine(2) })
 }
 
 runAllTests()

test/Prototypes/BigInt.swift

@@ -1064,17 +1064,9 @@ public struct _BigInt<Word: FixedWidthInteger & UnsignedInteger> :
 
   //===--- Hashable -------------------------------------------------------===//
 
-  public var hashValue: Int {
-#if arch(i386) || arch(arm)
-    let p: UInt = 16777619
-    let h: UInt = (2166136261 &* p) ^ (isNegative ? 1 : 0)
-#elseif arch(x86_64) || arch(arm64) || arch(powerpc64) || arch(powerpc64le) || arch(s390x)
-    let p: UInt = 1099511628211
-    let h: UInt = (14695981039346656037 &* p) ^ (isNegative ? 1 : 0)
-#else
-    fatalError("Unimplemented")
-#endif
-    return Int(bitPattern: _data.reduce(h, { ($0 &* p) ^ UInt($1) }))
+  public func hash(into hasher: inout Hasher) {
+    hasher.combine(isNegative)
+    hasher.combine(_data)
   }
 
   //===--- Bit shifting operators -----------------------------------------===//
@@ -1282,8 +1274,8 @@ struct Bit : FixedWidthInteger, UnsignedInteger {
 
   // Hashable, CustomStringConvertible
 
-  var hashValue: Int {
-    return Int(value)
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
   }
 
   var description: String {

test/Prototypes/CollectionTransformers.swift

@@ -206,8 +206,8 @@ import Dispatch
 public struct _stdlib_pthread_t : Equatable, Hashable {
   internal let _value: pthread_t
 
-  public var hashValue: Int {
-    return _value.hashValue
+  public func hash(into hasher: inout Hasher) {
+    hasher.combine(_value)
   }
 }
 

test/SIL/Parser/keypath.sil

@@ -10,7 +10,7 @@ struct S: Hashable {
   let y: String
   var z: C
 
-  var hashValue: Int { get }
+  func hash(into hasher: inout Hasher)
   static func ==(x: S, y: S) -> Bool
 }
 class C: Hashable {
@@ -23,7 +23,7 @@ class C: Hashable {
     get set
   }
 
-  var hashValue: Int { get }
+  func hash(into hasher: inout Hasher)
   static func ==(x: C, y: C) -> Bool
 }
 

test/SIL/Serialization/keypath.sil

@@ -14,7 +14,7 @@ struct S: Hashable {
   let y: String
   var z: C
 
-  var hashValue: Int { get }
+  func hash(into hasher: inout Hasher)
   static func ==(x: S, y: S) -> Bool
 }
 class C: Hashable {
@@ -27,7 +27,7 @@ class C: Hashable {
     get set
   }
 
-  var hashValue: Int { get }
+  func hash(into hasher: inout Hasher)
   static func ==(x: C, y: C) -> Bool
 }
 

test/SILGen/Inputs/ObjectiveC.swift

@@ -35,7 +35,7 @@ public struct Selector : ExpressibleByStringLiteral {
 }
 
 extension NSObject : Hashable {
-  public var hashValue: Int { return 0 }
+  public func hash(into hasher: inout Hasher) {}
   public static func == (x: NSObject, y: NSObject) -> Bool { return true }
 }
 

test/SILGen/Inputs/inherited_protocol_conformance_other_file_2_b.swift

@@ -1,3 +1,5 @@
 extension Thing : Hashable {
-    var hashValue: Int { return value }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
 }

test/SILGen/collection_cast_crash.swift

@@ -6,7 +6,7 @@
 class MyClass {}
 
 class KeyClass : Hashable {
-	var hashValue : Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 func ==(lhs: KeyClass, rhs: KeyClass) -> Bool { return true }
 

test/SILGen/collection_downcast.swift

@@ -20,7 +20,7 @@ class BridgedObjC : NSObject { }
 func == (x: BridgedObjC, y: BridgedObjC) -> Bool { return true }
 
 struct BridgedSwift : Hashable, _ObjectiveCBridgeable {
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 
   func _bridgeToObjectiveC() -> BridgedObjC {
     return BridgedObjC()

test/SILGen/collection_subtype_downcast.swift

@@ -17,8 +17,9 @@ func array_downcast(array: [Any]) -> [S]? {
 }
 
 extension S : Hashable {
-  var hashValue : Int {
-    return x + y
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(x)
+    hasher.combine(y)
   }
 }
 func ==(lhs: S, rhs: S) -> Bool {

test/SILGen/collection_subtype_upcast.swift

@@ -17,8 +17,9 @@ func array_upcast(array: [S]) -> [Any] {
 }
 
 extension S : Hashable {
-  var hashValue : Int {
-    return x + y
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(x)
+    hasher.combine(y)
   }
 }
 func ==(lhs: S, rhs: S) -> Bool {

test/SILGen/collection_upcast.swift

@@ -21,7 +21,7 @@ class BridgedObjC : NSObject { }
 func == (x: BridgedObjC, y: BridgedObjC) -> Bool { return true }
 
 struct BridgedSwift : Hashable, _ObjectiveCBridgeable {
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 
   func _bridgeToObjectiveC() -> BridgedObjC {
     return BridgedObjC()

test/SILGen/function_conversion.swift

@@ -605,10 +605,8 @@ func rdar35702810() {
 
 protocol X: Hashable {}
 class B: X {
-  var hashValue: Int { return 42 }
-  static func == (lhs: B, rhs: B) -> Bool {
-    return lhs.hashValue == rhs.hashValue
-  }
+  func hash(into hasher: inout Hasher) {}
+  static func == (lhs: B, rhs: B) -> Bool { return true }
 }
 
 func bar_arr<T: X>(type: T.Type, _ fn: ([T]?) -> Void) {}

test/SILGen/keypaths.swift

@@ -280,7 +280,7 @@ func iuoKeyPaths() {
 
 class Bass: Hashable {
   static func ==(_: Bass, _: Bass) -> Bool { return false }
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 
 class Treble: Bass { }

test/SILOptimizer/bridged_casts_folding.swift

@@ -924,9 +924,7 @@ class MyThing: Hashable {
         Swift.print("Deinit \(name)")
     }
 
-    var hashValue: Int {
-        return 0
-    }
+    func hash(into hasher: inout Hasher) {}
     
     static func ==(lhs: MyThing, rhs: MyThing) -> Bool {
         return false

test/SILOptimizer/di-loadable-by-addr-scope.swift

@@ -29,9 +29,9 @@ extension Version: Hashable {
         return lhs.major == rhs.major &&
                lhs.buildMetadataIdentifiers == rhs.buildMetadataIdentifiers
     }
-    public var hashValue: Int {
-        var result: UInt64 = 0
-        return Int(truncatingIfNeeded: result)
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(major)
+        hasher.combine(buildMetadataIdentifiers)
     }
 }
 

test/SILOptimizer/eager_specialize.sil

@@ -40,7 +40,7 @@ public func getGenericContainer<T>(g: G<T>, e: T.Elt) -> T where T.Elt : AnElt
 
 enum ArithmeticError : Error {
   case DivByZero
-  var hashValue: Int { get }
+  func hash(into hasher: inout Hasher)
   var _code: Int { get }
 }
 

test/SILOptimizer/specialize_inherited.sil

@@ -12,7 +12,7 @@ struct MMStorage<Key : Hashable, Value> {
 func ==(lhs: MMObject, rhs: MMObject) -> Bool
 
 class MMObject : Hashable {
-  var hashValue: Int { get }
+  func hash(into hasher: inout Hasher)
 }
 
 class MMString : MMObject {

test/Sema/enum_conformance_synthesis.swift

@@ -43,7 +43,7 @@ func localEnum() -> Bool {
 enum CustomHashable {
   case A, B
 
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 func ==(x: CustomHashable, y: CustomHashable) -> Bool {
   return true
@@ -239,7 +239,7 @@ extension OtherFileNonconforming: Hashable {
   static func ==(lhs: OtherFileNonconforming, rhs: OtherFileNonconforming) -> Bool {
     return true
   }
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 // ...but synthesis in a type defined in another file doesn't work yet.
 extension YetOtherFileNonconforming: Equatable {} // expected-error {{cannot be automatically synthesized in an extension in a different file to the type}}

test/Sema/struct_equatable_hashable.swift

@@ -48,9 +48,8 @@ struct CustomHashValue: Hashable {
   let x: Int
   let y: Int
 
-  var hashValue: Int { return 0 }
-
   static func ==(x: CustomHashValue, y: CustomHashValue) -> Bool { return true }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func customHashValue() {
@@ -192,7 +191,7 @@ extension OtherFileNonconforming: Hashable {
   static func ==(lhs: OtherFileNonconforming, rhs: OtherFileNonconforming) -> Bool {
     return true
   }
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 // ...but synthesis in a type defined in another file doesn't work yet.
 extension YetOtherFileNonconforming: Equatable {} // expected-error {{cannot be automatically synthesized in an extension in a different file to the type}}

test/attr/attr_objc.swift

@@ -2187,7 +2187,7 @@ class ConformsToProtocolThrowsObjCName2 : ProtocolThrowsObjCName {
 }
 
 @objc class ObjC_Class1 : Hashable {
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func ==(lhs: ObjC_Class1, rhs: ObjC_Class1) -> Bool {

test/attr/attr_objc_clang.swift

@@ -22,7 +22,7 @@ class infer_instanceVar1 {
 }
 
 class ObjC_Class1 : NSObject, Hashable {
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func ==(lhs: ObjC_Class1, rhs: ObjC_Class1) -> Bool {
@@ -30,7 +30,7 @@ func ==(lhs: ObjC_Class1, rhs: ObjC_Class1) -> Bool {
 }
 
 @objc class ObjC_Class2 : Hashable {
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func ==(lhs: ObjC_Class2, rhs: ObjC_Class2) -> Bool {

test/decl/protocol/special/coding/class_codable_nonconforming_property.swift

@@ -1,9 +1,7 @@
 // RUN: %target-typecheck-verify-swift -verify-ignore-unknown
 
 struct NonCodable : Hashable {
-    var hashValue: Int {
-        return 1
-    }
+    func hash(into hasher: inout Hasher) {}
 
     static func ==(_ lhs: NonCodable, _ rhs: NonCodable) -> Bool {
         return true

test/decl/protocol/special/coding/struct_codable_nonconforming_property.swift

@@ -1,9 +1,7 @@
 // RUN: %target-typecheck-verify-swift -verify-ignore-unknown
 
 struct NonCodable : Hashable {
-    var hashValue: Int {
-        return 1
-    }
+    func hash(into hasher: inout Hasher) {}
 
     static func ==(_ lhs: NonCodable, _ rhs: NonCodable) -> Bool {
         return true

test/expr/cast/dictionary_bridge.swift

@@ -13,9 +13,7 @@ public extension _ObjectiveCBridgeable {
 }
 
 class Root : Hashable {
-  var hashValue: Int {
-    return 0
-  }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func ==(x: Root, y: Root) -> Bool { return true }
@@ -42,9 +40,7 @@ struct BridgedToObjC : Hashable, _ObjectiveCBridgeable {
     return true
   }
 
-  var hashValue: Int {
-    return 0
-  }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func ==(x: BridgedToObjC, y: BridgedToObjC) -> Bool { return true }

test/expr/cast/dictionary_coerce.swift

@@ -3,8 +3,8 @@
 class C : Hashable {
 	var x = 0
 
-  var hashValue: Int {
-    return x
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(x)
   }
 }
 

test/expr/cast/dictionary_downcast.swift

@@ -3,8 +3,8 @@
 class C : Hashable {
 	var x = 0
 
-  var hashValue: Int {
-    return x
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(x)
   }
 }
 
@@ -15,9 +15,7 @@ class D : C {}
 
 // Unrelated to the classes above.
 class U : Hashable {
-  var hashValue: Int {
-    return 0
-  }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func == (x: U, y: U) -> Bool { return true }

test/expr/cast/optional.swift

@@ -1,7 +1,7 @@
 // RUN: %target-typecheck-verify-swift
 
 class Base : Hashable {
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 
 class Derived : Base { }

test/expr/cast/set_bridge.swift

@@ -13,9 +13,7 @@ public extension _ObjectiveCBridgeable {
 }
 
 class Root : Hashable {
-  var hashValue: Int {
-    return 0
-  }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func ==(x: Root, y: Root) -> Bool { return true }
@@ -44,9 +42,7 @@ struct BridgedToObjC : Hashable, _ObjectiveCBridgeable {
     return true
   }
 
-  var hashValue: Int {
-    return 0
-  }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func ==(x: BridgedToObjC, y: BridgedToObjC) -> Bool { return true }

test/expr/cast/set_coerce.swift

@@ -3,8 +3,8 @@
 class C : Hashable {
 	var x = 0
 
-  var hashValue: Int {
-    return x
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(x)
   }
 }
 

test/expr/cast/set_downcast.swift

@@ -3,8 +3,8 @@
 class C : Hashable {
 	var x = 0
 
-  var hashValue: Int {
-    return x
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(x)
   }
 }
 
@@ -15,9 +15,7 @@ class D : C {}
 
 // Unrelated to the classes above.
 class U : Hashable { 
-  var hashValue: Int {
-    return 0
-  }
+  func hash(into hasher: inout Hasher) {}
 }
 
 func == (x: U, y: U) -> Bool { return true }

test/expr/unary/keypath/keypath.swift

@@ -2,11 +2,11 @@
 
 struct Sub: Hashable {
   static func ==(_: Sub, _: Sub) -> Bool { return true }
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 struct OptSub: Hashable {
   static func ==(_: OptSub, _: OptSub) -> Bool { return true }
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 struct NonHashableSub {}
 
@@ -33,7 +33,7 @@ struct A: Hashable {
   subscript(sub: Sub) -> A { get { return self } set { } }
 
   static func ==(_: A, _: A) -> Bool { fatalError() }
-  var hashValue: Int { fatalError() }
+  func hash(into hasher: inout Hasher) { fatalError() }
 }
 struct B {}
 struct C<T> {
@@ -486,7 +486,7 @@ func testStaticKeyPathComponent() {
 
 class Bass: Hashable {
   static func ==(_: Bass, _: Bass) -> Bool { return false }
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 }
 
 class Treble: Bass { }

test/stdlib/AnyHashableCasts.swift.gyb

@@ -26,7 +26,9 @@ struct HashableStruct : Hashable {
   static func ==(lhs: HashableStruct, rhs: HashableStruct) -> Bool {
     return lhs.value == rhs.value
   }
-  var hashValue : Int { return value }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
 }
 
 class HashableClass : Hashable {
@@ -35,7 +37,9 @@ class HashableClass : Hashable {
   static func ==(lhs: HashableClass, rhs: HashableClass) -> Bool {
     return lhs.value == rhs.value
   }
-  var hashValue : Int { return value }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
 }
 
 enum HashableEnum : Hashable {
@@ -45,9 +49,10 @@ enum HashableEnum : Hashable {
     case (.value(let l), .value(let r)): return l == r
     }
   }
-  var hashValue : Int {
+  func hash(into hasher: inout Hasher) {
     switch self {
-    case .value(let v): return v
+    case .value(let v):
+      hasher.combine(v)
     }
   }
 }

test/stdlib/BinaryIntegerRequirements.swift

@@ -42,7 +42,7 @@ struct MyInt: FixedWidthInteger { // expected-error {{type 'MyInt' does not conf
   func quotientAndRemainder(dividingBy rhs: MyInt) -> (quotient: MyInt, remainder: MyInt) { fatalError() }
   func signum() -> MyInt { fatalError() }
 
-  var hashValue: Int { fatalError() }
+  func hash(into hasher: inout Hasher) { fatalError() }
   var byteSwapped: MyInt { fatalError() }
   static var max: MyInt { fatalError() }
   static var min: MyInt { fatalError() }

test/stdlib/BridgeIdAsAny.swift.gyb

@@ -33,8 +33,9 @@ struct KnownUnbridged: Equatable, Hashable {
     return a.x === b.x && a.y === b.y
   }
 
-  public var hashValue: Int {
-    return x.hashValue ^ y.hashValue
+  public func hash(into hasher: inout Hasher) {
+    hasher.combine(x)
+    hasher.combine(y)
   }
 }
 

test/stdlib/Inputs/DictionaryKeyValueTypesObjC.swift

@@ -235,6 +235,10 @@ var _bridgedKeyBridgeOperations = _stdlib_AtomicInt(0)
 
 struct TestBridgedKeyTy
   : Equatable, Hashable, CustomStringConvertible, _ObjectiveCBridgeable {
+  var value: Int
+  var _hashValue: Int
+  var serial: Int
+
   static var bridgeOperations: Int {
     get {
       return _bridgedKeyBridgeOperations.load()
@@ -259,6 +263,10 @@ struct TestBridgedKeyTy
     return _hashValue
   }
 
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(_hashValue)
+  }
+
   func _bridgeToObjectiveC() -> TestObjCKeyTy {
     _bridgedKeyBridgeOperations.fetchAndAdd(1)
     return TestObjCKeyTy(value)
@@ -286,10 +294,6 @@ struct TestBridgedKeyTy
     _forceBridgeFromObjectiveC(source!, result: &result)
     return result!
   }
-
-  var value: Int
-  var _hashValue: Int
-  var serial: Int
 }
 
 func == (lhs: TestBridgedKeyTy, rhs: TestBridgedKeyTy) -> Bool {

test/stdlib/Integers.swift.gyb

@@ -96,8 +96,8 @@ extension MockBinaryInteger : Comparable {
 }
 
 extension MockBinaryInteger : Hashable {
-  var hashValue: Int {
-    return _value.hashValue
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(_value)
   }
 }
 

test/stdlib/KeyPath.swift

@@ -592,7 +592,9 @@ struct KeyA: Hashable {
   init(value: String) { self.value = value }
 
   static func ==(a: KeyA, b: KeyA) -> Bool { return a.value == b.value }
-  var hashValue: Int { return value.hashValue }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
 }
 struct KeyB: Hashable {
   var canary = LifetimeTracked(2222)
@@ -602,7 +604,9 @@ struct KeyB: Hashable {
   init(value: Int) { self.value = value }
 
   static func ==(a: KeyB, b: KeyB) -> Bool { return a.value == b.value }
-  var hashValue: Int { return value.hashValue }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
 }
 
 func fullGenericContext<T: Hashable, U: Hashable>(x: T, y: U) -> KeyPath<Subscripts<T>, SubscriptResult<T, U>> {

test/stdlib/OptionalBridge.swift

@@ -70,7 +70,9 @@ tests.test("wrapped value") {
 struct NotBridged: Hashable {
   var x: Int
 
-  var hashValue: Int { return x }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(x)
+  }
 
   static func ==(x: NotBridged, y: NotBridged) -> Bool {
     return x.x == y.x

test/stdlib/SetTrapsObjC.swift

@@ -18,8 +18,8 @@ struct NotBridgedKeyTy : Equatable, Hashable {
   init(_ value: Int) {
     self.value = value
   }
-  var hashValue: Int {
-    return value
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
   }
   var value: Int
 }
@@ -38,8 +38,8 @@ class BridgedVerbatimRefTy : Equatable, Hashable {
   init(_ value: Int) {
     self.value = value
   }
-  var hashValue: Int {
-    return value
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
   }
   var value: Int
 }
@@ -83,7 +83,9 @@ class TestObjCKeyTy : NSObject {
 struct TestBridgedKeyTy : Hashable, _ObjectiveCBridgeable {
   init(_ value: Int) { self.value = value }
 
-  var hashValue: Int { return value }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
 
   func _bridgeToObjectiveC() -> TestObjCKeyTy {
     return TestObjCKeyTy(value)

test/stdlib/TestUserInfo.swift

@@ -42,7 +42,12 @@ struct SomeStructure: Hashable {
     }
 
     // FIXME: we don't care about this, but Any only finds == on Hashables
-    var hashValue: Int { return i }
+    func hash(into hasher: inout Hasher) {
+        hasher.combine(i)
+        hasher.combine(str)
+        hasher.combine(sub.i)
+        hasher.combine(sub.str)
+    }
 }
 
 /*

test/type/dictionary.swift

@@ -35,7 +35,7 @@ struct NotHashable { }
 var nh1 : [NotHashable : Int] // expected-error{{'NotHashable' does not conform to protocol 'Hashable'}}
 
 struct Y<T> : Hashable {
-  var hashValue: Int { return 0 }
+  func hash(into hasher: inout Hasher) {}
 
   static func ==(this: Y<T>, other: Y<T>) -> Bool { return true }
 }

validation-test/stdlib/AnyHashable.swift.gyb

@@ -214,6 +214,9 @@ ${kw} HasCustomRepresentation_${name}
   var hashValue: Int {
     return value
   }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
   func _toCustomAnyHashable() -> AnyHashable? {
     if hasDefaultAnyHashableRepresentation {
       return nil
@@ -248,6 +251,9 @@ ${kw} HasCustomRepresentation_Generic${name}<Wrapped>
   var hashValue: Int {
     return asGenericMinimalHashableValue.hashValue
   }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(asGenericMinimalHashableValue)
+  }
   func _toCustomAnyHashable() -> AnyHashable? {
     if hasDefaultAnyHashableRepresentation {
       return nil
@@ -360,6 +366,9 @@ struct HasCustomRepresentationRecursively
   var hashValue: Int {
     return value
   }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
   func _toCustomAnyHashable() -> AnyHashable? {
     if value == 0 {
       return AnyHashable(HasCustomRepresentationRecursively(value + 1))
@@ -457,6 +466,9 @@ class ${hashable_base.full_name} : ${', '.join([b.full_name for b in bases])} {
   var hashValue: Int {
     return value
   }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
   static func == ${hashable_base.generic_parameters_decl} (
     lhs: ${hashable_base.full_name},
     rhs: ${hashable_base.full_name}
@@ -697,14 +709,14 @@ enum MinimalHashableRCSwiftError : Error, Hashable {
   case caseB(LifetimeTracked)
   case caseC(LifetimeTracked)
 
-  var hashValue: Int {
+  func hash(into hasher: inout Hasher) {
     switch self {
     case .caseA:
-      return 10
+      hasher.combine(10)
     case .caseB:
-      return 20
+      hasher.combine(20)
     case .caseC:
-      return 30
+      hasher.combine(30)
     }
   }
 

validation-test/stdlib/CollectionCasts.swift.gyb

@@ -18,12 +18,12 @@
 import StdlibUnittest
 
 class Base : Hashable {
+  var value: Int
   init(_ value: Int) {
     self.value = value
   }
-  var value: Int
-  var hashValue : Int {
-    return value.hashValue
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
   }
 }
 

validation-test/stdlib/DictionaryTrapsObjC.swift

@@ -17,13 +17,15 @@ let testSuiteSuffix = _isDebugAssertConfiguration() ? "_debug" : "_release"
 var DictionaryTraps = TestSuite("DictionaryTraps" + testSuiteSuffix)
 
 struct NotBridgedKeyTy : Equatable, Hashable {
+  var value: Int
+
   init(_ value: Int) {
     self.value = value
   }
-  var hashValue: Int {
-    return value
+
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
   }
-  var value: Int
 }
 
 func == (lhs: NotBridgedKeyTy, rhs: NotBridgedKeyTy) -> Bool {
@@ -37,13 +39,14 @@ struct NotBridgedValueTy {}
 assert(!_isBridgedToObjectiveC(NotBridgedValueTy.self))
 
 class BridgedVerbatimRefTy : Equatable, Hashable {
+  var value: Int
+
   init(_ value: Int) {
     self.value = value
   }
-  var hashValue: Int {
-    return value
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
   }
-  var value: Int
 }
 
 func == (lhs: BridgedVerbatimRefTy, rhs: BridgedVerbatimRefTy) -> Bool {
@@ -81,9 +84,13 @@ class TestObjCKeyTy : NSObject {
 }
 
 struct TestBridgedKeyTy : Hashable, _ObjectiveCBridgeable {
+  var value: Int
+
   init(_ value: Int) { self.value = value }
 
-  var hashValue: Int { return value }
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
+  }
 
   func _bridgeToObjectiveC() -> TestObjCKeyTy {
     return TestObjCKeyTy(value)
@@ -110,8 +117,6 @@ struct TestBridgedKeyTy : Hashable, _ObjectiveCBridgeable {
     _forceBridgeFromObjectiveC(source!, result: &result)
     return result!
   }
-
-  var value: Int
 }
 
 func ==(x: TestBridgedKeyTy, y: TestBridgedKeyTy) -> Bool {

validation-test/stdlib/SetAlgebra.swift

@@ -5,8 +5,8 @@ import StdlibUnittest
 import StdlibCollectionUnittest
 
 extension MinimalEquatableValue : Hashable {
-  public var hashValue: Int {
-    return value
+  public func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
   }
 }
 

validation-test/stdlib/SetAnyHashableExtensions.swift

@@ -10,8 +10,8 @@ class TestHashableBase : Hashable {
     self.value = value
     self.identity = identity
   }
-  var hashValue: Int {
-    return value
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(value)
   }
   static func == (
     lhs: TestHashableBase,